The present invention relates to a gate valve and more particularly to a non-sliding gate valve for high vacuum use.
Recently, as further integration of semiconductors as well as the variety and complexity of their constitutions, etc. have progressed, the requirements for maintaining cleanliness in the manufacturing environment have come even more stringent.
Gate valves are essential constitutional elements for equipment for manufacturing semiconductors, and the greater part of the mechanism for opening and closing their valve bodies are provided within a vacuum environment. For example, as a mechanism for transferring force to urge the packing of a valve body against the valve seat and to maintain a seal between them mechanisms using a linkage, or types pushing a wedge between them, etc. have been known, and these mechanisms are as a rule provided within a vacuum environment. Further, other link mechanisms may also be provided in the valve rod to actuate the valve body in order to absorb its stroke, and it is not rare to have such mechanisms also provided within a vacuum environment as well.
Moreover, when these mechanisms are provided within a vacuum environment, regardless of whether their operation is rolling or shifting, if frictional movement accompanies their operation minute particles (particles of different materials) are unavoidably produced as a result of the friction, damaging the requirements for a high degree of cleanliness in the vacuum environment, prohibiting the use of such mechanisms. Further, as a countermeasure for decreasing frictional resistance in cases where friction accompanies operation of the gate valves the mechanisms need to be lubricated by some suitable medium, but, since it is very difficult to adopt such a countermeasure within a vacuum environment it is often the case that clogging will occur at the frictional parts if continuous operation takes place at high frequency. In the mechanical device it is also a difficult situation when the mechanical portion includes a frictional element.